# Copyright 2008-2015 Free Software Foundation, Inc.
# This file is part of GNU Radio
#
# SPDX-License-Identifier: GPL-2.0-or-later
#


import collections
import itertools
import types
import logging
import yaml
from operator import methodcaller, attrgetter
from typing import (List, Set, Optional, Iterator, Iterable, Tuple, Union, OrderedDict)

from . import Messages
from .base import Element
from .blocks import Block
from .params import Param
from .utils import expr_utils

log = logging.getLogger(__name__)


class FlowGraph(Element):

    is_flow_graph = True

    def __init__(self, parent: Element):
        """
        Make a flow graph from the arguments.

        Args:
            parent: a platforms with blocks and element factories

        Returns:
            the flow graph object
        """
        Element.__init__(self, parent)
        self.options_block: Block = self.parent_platform.make_block(self, 'options')

        self.blocks = [self.options_block]
        self.connections = set()

        self._eval_cache = {}
        self.namespace = {}
        self.imported_names = []

        self.grc_file_path = ''

    def __str__(self) -> str:
        return f"FlowGraph - {self.get_option('title')}({self.get_option('id')})"

    def imports(self) -> List[str]:
        """
        Get a set of all import statements (Python) in this flow graph namespace.

        Returns:
            a list of import statements
        """
        return [block.templates.render('imports') for block in self.iter_enabled_blocks()]

    def get_variables(self) -> List[str]:
        """
        Get a list of all variables (Python) in this flow graph namespace.
        Exclude parameterized variables.

        Returns:
            a sorted list of variable blocks in order of dependency (indep -> dep)
        """
        variables = [block for block in self.iter_enabled_blocks()
                     if block.is_variable]
        return expr_utils.sort_objects(variables, attrgetter('name'), methodcaller('get_var_make'))

    def get_parameters(self) -> List[Element]:
        """
        Get a list of all parameterized variables in this flow graph namespace.

        Returns:
            a list of parameterized variables
        """
        parameters = [b for b in self.iter_enabled_blocks()
                      if b.key == 'parameter']
        return parameters

    def _get_snippets(self) -> List[Element]:
        """
        Get a set of all code snippets (Python) in this flow graph namespace.

        Returns:
            a list of code snippets
        """
        return [b for b in self.iter_enabled_blocks() if b.key == 'snippet']

    def get_snippets_dict(self, section=None) -> List[dict]:
        """
        Get a dictionary of code snippet information for a particular section.

        Args:
            section: string specifier of section of snippets to return, section=None returns all

        Returns:
            a list of code snippets dicts
        """
        snippets = self._get_snippets()
        if not snippets:
            return []

        output = []
        for snip in snippets:
            d = {}
            sect = snip.params['section'].value
            d['section'] = sect
            d['priority'] = snip.params['priority'].value
            d['lines'] = snip.params['code'].value.splitlines()
            d['def'] = 'def snipfcn_{}(self):'.format(snip.name)
            d['call'] = 'snipfcn_{}(tb)'.format(snip.name)
            if not len(d['lines']):
                Messages.send_warning("Ignoring empty snippet from canvas")
            else:
                if not section or sect == section:
                    output.append(d)

        # Sort by descending priority
        if section:
            output = sorted(output, key=lambda x: x['priority'], reverse=True)

        return output

    def get_monitors(self) -> List[Element]:
        """
        Get a list of all ControlPort monitors
        """
        monitors = [b for b in self.iter_enabled_blocks()
                    if 'ctrlport_monitor' in b.key]
        return monitors

    def get_python_modules(self) -> Iterator[Tuple[str, str]]:
        """Iterate over custom code block ID and Source"""
        for block in self.iter_enabled_blocks():
            if block.key == 'epy_module':
                yield block.name, block.params['source_code'].get_value()

    def iter_enabled_blocks(self) -> Iterator[Element]:
        """
        Get an iterator of all blocks that are enabled and not bypassed.
        """
        return (block for block in self.blocks if block.enabled)

    def get_enabled_blocks(self) -> List[Element]:
        """
        Get a list of all blocks that are enabled and not bypassed.

        Returns:
            a list of blocks
        """
        return list(self.iter_enabled_blocks())

    def get_bypassed_blocks(self) -> List[Element]:
        """
        Get a list of all blocks that are bypassed.

        Returns:
            a list of blocks
        """
        return [block for block in self.blocks if block.get_bypassed()]

    def get_enabled_connections(self) -> List[Element]:
        """
        Get a list of all connections that are enabled.

        Returns:
            a list of connections
        """
        return [connection for connection in self.connections if connection.enabled]

    def get_option(self, key) -> Param.EvaluationType:
        """
        Get the option for a given key.
        The option comes from the special options block.

        Args:
            key: the param key for the options block

        Returns:
            the value held by that param
            will return None if the key param key doesn't exist
        """
        param = self.options_block.params.get(key)
        if param:
            return param.get_evaluated()
        else:
            return None

    def get_imported_names(self) -> Set[str]:
        """
        Get a list of imported names.
        These names may not be used as id's

        Returns:
            a list of imported names
        """
        return self.imported_names

    ##############################################
    # Access Elements
    ##############################################
    def get_block(self, name) -> Block:
        for block in self.blocks:
            if block.name == name:
                return block
        raise KeyError(f'No block with name {repr(name)}')

    def get_elements(self) -> List[Element]:
        elements = list(self.blocks)
        elements.extend(self.connections)
        return elements

    def children(self) -> Iterable[Element]:
        return itertools.chain(self.blocks, self.connections)

    def rewrite(self):
        """
        Flag the namespace to be renewed.
        """
        self._renew_namespace()
        Element.rewrite(self)

    def _reload_imports(self, namespace: dict) -> dict:
        """
        Load imports; be tolerant about import errors
        """
        for expr in self.imports():
            try:
                exec(expr, namespace)
            except ImportError:
                # We do not have a good way right now to determine if an import is for a
                # hier block, these imports will fail as they are not in the search path
                # this is ok behavior, unfortunately we could be hiding other import bugs
                pass
            except Exception:
                log.exception(f"Failed to evaluate import expression \"{expr}\"", exc_info=True)
                pass
        return namespace

    def _reload_modules(self, namespace: dict) -> dict:
        for id, expr in self.get_python_modules():
            try:
                module = types.ModuleType(id)
                exec(expr, module.__dict__)
                namespace[id] = module
            except Exception:
                log.exception(f'Failed to evaluate expression in module {id}', exc_info=True)
                pass
        return namespace

    def _reload_parameters(self, namespace: dict) -> dict:
        """
        Load parameters. Be tolerant of evaluation failures.
        """
        np = {}  # params don't know each other
        for parameter_block in self.get_parameters():
            try:
                value = eval(
                    parameter_block.params['value'].to_code(), namespace)
                np[parameter_block.name] = value
            except Exception:
                log.exception(f'Failed to evaluate parameter block {parameter_block.name}', exc_info=True)
                pass
        namespace.update(np)  # Merge param namespace
        return namespace

    def _reload_variables(self, namespace: dict) -> dict:
        """
        Load variables. Be tolerant of evaluation failures.
        """
        for variable_block in self.get_variables():
            try:
                variable_block.rewrite()
                value = eval(variable_block.value, namespace,
                             variable_block.namespace)
                namespace[variable_block.name] = value
                # rewrite on subsequent blocks depends on an updated self.namespace
                self.namespace.update(namespace)
            # The following Errors may happen, but that doesn't matter as they are displayed in the gui
            except (TypeError, FileNotFoundError, AttributeError, yaml.YAMLError):
                pass
            except Exception:
                log.exception(f'Failed to evaluate variable block {variable_block.name}', exc_info=True)
        return namespace

    def _renew_namespace(self) -> None:
        # Before renewing the namespace, clear it
        # to get rid of entries of blocks that
        # are no longer valid ( deleted, disabled, ...)
        self.namespace.clear()

        namespace = self._reload_imports({})
        self.imported_names = set(namespace.keys())
        namespace = self._reload_modules(namespace)
        namespace = self._reload_parameters(namespace)

        # We need the updated namespace to evaluate the variable blocks
        # otherwise sometimes variable_block rewrite / eval fails
        self.namespace.update(namespace)
        namespace = self._reload_variables(namespace)
        self._eval_cache.clear()

    def evaluate(self, expr: str, namespace: Optional[dict] = None, local_namespace: Optional[dict] = None):
        """
        Evaluate the expression within the specified global and local namespaces
        """
        # Evaluate
        if not expr:
            raise Exception('Cannot evaluate empty statement.')
        if namespace is not None:
            return eval(expr, namespace, local_namespace)
        else:
            return self._eval_cache.setdefault(expr, eval(expr, self.namespace, local_namespace))

    ##############################################
    # Add/remove stuff
    ##############################################

    def new_block(self, block_id, **kwargs) -> Block:
        """
        Get a new block of the specified key.
        Add the block to the list of elements.

        Args:
            block_id: the block key

        Returns:
            the new block or None if not found
        """
        if block_id == 'options':
            return self.options_block
        try:
            block = self.parent_platform.make_block(self, block_id, **kwargs)
            self.blocks.append(block)
        except KeyError:
            block = None
        return block

    def connect(self, porta, portb, params=None):
        """
        Create a connection between porta and portb.

        Args:
            porta: a port
            portb: another port
        @throw Exception bad connection

        Returns:
            the new connection
        """
        connection = self.parent_platform.Connection(
            parent=self, source=porta, sink=portb)
        if params:
            connection.import_data(params)
        self.connections.add(connection)

        return connection

    def disconnect(self, *ports) -> None:
        to_be_removed = [con for con in self.connections
                         if any(port in con for port in ports)]
        for con in to_be_removed:
            self.remove_element(con)

    def remove_element(self, element) -> None:
        """
        Remove the element from the list of elements.
        If the element is a port, remove the whole block.
        If the element is a block, remove its connections.
        If the element is a connection, just remove the connection.
        """
        if element is self.options_block:
            return

        if element.is_port:
            element = element.parent_block  # remove parent block

        if element in self.blocks:
            # Remove block, remove all involved connections
            self.disconnect(*element.ports())
            self.blocks.remove(element)

        elif element in self.connections:
            self.connections.remove(element)

    ##############################################
    # Import/Export Methods
    ##############################################
    def export_data(self) -> OrderedDict[str, str]:
        """
        Export this flow graph to nested data.
        Export all block and connection data.

        Returns:
            a nested data odict
        """
        def block_order(b):
            return not b.is_variable, b.name  # todo: vars still first ?!?

        def get_file_format_version(data) -> int:
            """Determine file format version based on available data"""
            if any(isinstance(c, dict) for c in data['connections']):
                return 2
            return 1

        def sort_connection_key(connection_info) -> List[str]:
            if isinstance(connection_info, dict):
                return [connection_info.get(key) for key in ('src_blk_id', 'src_port_id', 'snk_blk_id', 'snk_port_id')]
            return connection_info
        data = collections.OrderedDict()
        data['options'] = self.options_block.export_data()
        data['blocks'] = [b.export_data() for b in sorted(self.blocks, key=block_order)
                          if b is not self.options_block]
        data['connections'] = sorted(
            (c.export_data() for c in self.connections),
            key=sort_connection_key)

        data['metadata'] = {
            'file_format': get_file_format_version(data),
            'grc_version': self.parent_platform.config.version
        }
        return data

    def _build_depending_hier_block(self, block_id) -> Optional[Block]:
        # we're before the initial fg update(), so no evaluated values!
        # --> use raw value instead
        path_param = self.options_block.params['hier_block_src_path']
        file_path = self.parent_platform.find_file_in_paths(
            filename=block_id + '.grc',
            paths=path_param.get_value(),
            cwd=self.grc_file_path
        )
        if file_path:  # grc file found. load and get block
            self.parent_platform.load_and_generate_flow_graph(
                file_path, hier_only=True)
            return self.new_block(block_id)  # can be None

    def import_data(self, data) -> bool:
        """
        Import blocks and connections into this flow graph.
        Clear this flow graph of all previous blocks and connections.
        Any blocks or connections in error will be ignored.

        Args:
            data: the nested data odict

        Returns:
            connection_error bool signifying whether a connection error happened.
        """
        # Remove previous elements
        del self.blocks[:]
        self.connections.clear()

        file_format = data['metadata']['file_format']

        # build the blocks
        self.options_block.import_data(name='', **data.get('options', {}))
        self.options_block.insert_grc_parameters(data['options']['parameters'])
        self.blocks.append(self.options_block)

        for block_data in data.get('blocks', []):
            block_id = block_data['id']
            block = (
                self.new_block(block_id) or
                self._build_depending_hier_block(block_id) or
                self.new_block(block_id='_dummy',
                               missing_block_id=block_id, **block_data)
            )

            block.import_data(**block_data)

        self.rewrite()

        # build the connections
        def verify_and_get_port(key, block, dir):
            ports = block.sinks if dir == 'sink' else block.sources
            for port in ports:
                if key == port.key or key + '0' == port.key:
                    break
                if not key.isdigit() and port.dtype == '' and key == port.name:
                    break
            else:
                if block.is_dummy_block:
                    port = block.add_missing_port(key, dir)
                else:
                    raise LookupError(f"{dir} key {key} not in {dir} block keys")
            return port

        had_connect_errors = False
        _blocks = {block.name: block for block in self.blocks}

        # TODO: Add better error handling if no connections exist in the flowgraph file.
        for connection_info in data.get('connections', []):
            # First unpack the connection info, which can be in different formats.
            # FLOW_GRAPH_FILE_FORMAT_VERSION 1: Connection info is a 4-tuple
            if isinstance(connection_info, (list, tuple)) and len(connection_info) == 4:
                src_blk_id, src_port_id, snk_blk_id, snk_port_id = connection_info
                conn_params = {}
            # FLOW_GRAPH_FILE_FORMAT_VERSION 2: Connection info is a dictionary
            elif isinstance(connection_info, dict):
                src_blk_id = connection_info.get('src_blk_id')
                src_port_id = connection_info.get('src_port_id')
                snk_blk_id = connection_info.get('snk_blk_id')
                snk_port_id = connection_info.get('snk_port_id')
                conn_params = connection_info.get('params', {})
            else:
                Messages.send_error_load('Invalid connection format detected!')
                had_connect_errors = True
                continue
            try:
                source_block = _blocks[src_blk_id]
                sink_block = _blocks[snk_blk_id]

                # fix old, numeric message ports keys
                if file_format < 1:
                    src_port_id, snk_port_id = _update_old_message_port_keys(
                        src_port_id, snk_port_id, source_block, sink_block)

                # build the connection
                source_port = verify_and_get_port(
                    src_port_id, source_block, 'source')
                sink_port = verify_and_get_port(
                    snk_port_id, sink_block, 'sink')

                self.connect(source_port, sink_port, conn_params)

            except (KeyError, LookupError) as e:
                Messages.send_error_load(
                    f"""Connection between {src_blk_id}({src_port_id}) and {snk_blk_id}({snk_port_id}) could not be made
                    \t{e}""")
                had_connect_errors = True

        for block in self.blocks:
            if block.is_dummy_block:
                block.rewrite()      # Make ports visible
                # Flowgraph errors depending on disabled blocks are not displayed
                # in the error dialog box
                # So put a message into the Property window of the dummy block
                block.add_error_message(f'Block id "{block.key}" not found.')

        self.rewrite()  # global rewrite
        return had_connect_errors


def _update_old_message_port_keys(source_key, sink_key, source_block, sink_block) -> Tuple[str, str]:
    """
    Backward compatibility for message port keys

    Message ports use their names as key (like in the 'connect' method).
    Flowgraph files from former versions still have numeric keys stored for
    message connections. These have to be replaced by the name of the
    respective port. The correct message port is deduced from the integer
    value of the key (assuming the order has not changed).

    The connection ends are updated only if both ends translate into a
    message port.
    """
    try:
        # get ports using the "old way" (assuming linear indexed keys)
        source_port = source_block.sources[int(source_key)]
        sink_port = sink_block.sinks[int(sink_key)]
        if source_port.dtype == "message" and sink_port.dtype == "message":
            source_key, sink_key = source_port.key, sink_port.key
    except (ValueError, IndexError):
        pass
    return source_key, sink_key  # do nothing
